The present invention relates to a graphic emulation method in a printer, and more particularly to a dot matrix printing graphic emulation method in a page printer adopting band buffering system.
Generally, inputted image data for use in a dot matrix printer is directly used to image data for use in a page printer without being filtering in the page printer.
FIG. 1 shows a method forming printing fonts of the image data in an 8-pin dot matrix printer. In order to form printing fonts of the dot matrix image data by the unit of line in the page printer, the position of bits of the dot matrix image data is checked as shown in FIG. 2. Then dots having a value of "1" are connected to form line segments as indicated in FIG. 3. The line segments are stored to a frame buffer in a full buffering system. The full buffering system sets data of the unit of page to a memory in the form of 2-dimensional array. The memory stores character image data, graphic image data, etc. in response to control commands in the printer and transmits the contents of the buffer to an engine by page output control command. In the band buffering system, the line segments are stored to a symbolic buffer 402 of FIG. 4. The symbolic buffer 402 generally has a linked list shape as shown in FIG. 4.
However, since there is no filtering processes in receiving the image data regardless of the image data form, when overwriting, space fill-in, etc. are used to obtain a clear image in a dot matrix printer, various ineffective aspects occur in converting to a different printing method. When performing the overwriting in the dot matrix printer, if the control input is "TEST PRINT", bold image is obtained by repeatedly printing the printing fonts onto the same position as shown in FIG. 5 however, in the case of the page printer incapable of controlling the difference of density of dots (that is, whether a dot is printed or not), since the overwriting is not implemented, the processing time is delayed and the memory space wastes.
As shown in FIG. 6C, the space fill-in using image data of FIG. 6A and the image data line-fed by 0.5 dots of FIG. 6B is performed in the dot matrix printer to compensate the degradation of picture quality generated by the interval between mechanically designed vertical pins. However, from the emulation method in the conventional page printer, the line segments having the same thickness are generated every interval, and as a result, the space fill-in has no effect on the picture quality and leads to the delay of the processing time.